Mobile robot

ABSTRACT

A mobile robot configured to be widely versatile in its use. For example, the mobile robot can be configured for being used on a wide assortment of surfaces, regardless of the orientation and/or shape of the surfaces. Alternatively or in combination, the mobile robot can be configured for effective and efficient movement on the surfaces it traverses. In some cases, the mobile robot is configured with two or more component units. In some cases, the component units are configured with magnets and a control system for orientating the magnets. In some cases, one or more component couplings join the component units. In some cases, the mobile unit is configured with Mecanum wheels.

CROSS-REFERENCES

This application is a continuation of U.S. application Ser. No.13/690,951, filed Nov. 30, 2012, which claimed the benefit of both U.S.Provisional Application No. 61/566,104, filed Dec. 2, 2011, and U.S.Provisional Application No. 61/703,656, filed Sep. 20, 2012, thecontents of which are hereby incorporated by reference in theirrespective entireties.

FIELD OF THE INVENTION

The present invention relates to mobile robots.

SUMMARY OF THE INVENTION

Embodiments of the present invention involve a mobile robot configuredto be widely versatile in its use. For example, the mobile robot can beconfigured for being used on a wide assortment of surfaces, regardlessof the orientation and/or shape of the surfaces. Alternatively or incombination, the mobile robot can be configured for effective andefficient movement on the surfaces it traverses.

In certain embodiments, the mobile robot is configured to be used on asurface, regardless of the surface's orientation to the ground or floor.For example, when designed for use on ferromagnetic surfaces, the robotcan include magnets and orientation control structure therefor. In suchcases, the magnets are operatively coupled to the robot so as to be heldabove, i.e., having no direct contact with, the ferromagnetic surfaces,yet the field strengths of the magnets are sufficient to hold the robotand its payload against the surfaces without risk of falling therefrom.In some cases, the magnets are operably coupled to outer ends of therobot so as to keep at a minimum one or more of the robot frame'sclearance from the surfaces it traverses, the robot's center of gravity,and the robot's overall profile. In some cases, the magnets areselectively adjustable in two or more dimensions in relation to theferromagnetic surfaces. In some cases, the magnets are operably coupledto opposing ends of the robot. In some cases, the magnets are externallyoffset from component units of the robot. In some cases, the mobilerobot is configurable to have a ganged configuration in conjunction withusing the magnets and their orientation control structure.

In certain embodiments, the mobile robot is configured to be used on asurface, regardless of the surface's shape. For example, when used oncurved surfaces, the robot can include two or more component units thatare operatively joined together via one or more linkages. In such cases,the linkages are configured to join two component units, yet permit theunits to shift in relation to each other so as to adapt to the shape ofthe surfaces on which the robot is used. Consequently, the mobile robotcan be self-adapting to any of a variety of surface shapes so contactbetween the robot and surfaces is sufficiently maintained during therobot's use. In some cases, the one or more linkages are locatedexternal to component units. In some cases, the one or more linkages areoperably coupled to outer sides of two of the component units. In somecases, the one or more linkages are located along a midline of therobot, being located apart from wheel axles of the robot. In some cases,the one or more linkages are configured for at least pivoting one of thecomponent units in relation to the other component unit.

In certain embodiments, the mobile robot is configured to have botheffective and efficient movement on a surface. For example, the robotcan include omni-directional wheels to facilitate movement of the robotin any direction. In such cases, the robot would not dictate steeringassembly, which is generally limited to moving only certain wheels fornavigation. To the contrary, each of the wheels can be independentlycontrolled, enabling the robot's drive type to be versatile and therobot's change of direction capability to be more precise and immediateas opposed to using conventional wheels with steering mechanism. In onecase, the robot can be configured with Mecanum wheels.

These and other aspects and features of the invention will be more fullyunderstood and appreciated by reference to the appended drawings and thedescription of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a mobile robot with locked componentunits in accordance with certain embodiments of the invention;

FIG. 2 is an elevation view of one side of the robot of FIG. 1, whereinthe robot is shown on an object with curved surface;

FIG. 3 is a graph showing force vs. distance relationship for magnet ofneodymium material in relation to a ferrous surface;

FIG. 4 is a perspective view of a mobile robot stemming from the robotof FIG. 1 in accordance with certain embodiments of the invention,including a differing magnet mount and being shown on an object withcurved surface;

FIG. 5 is a perspective view of the magnet mount of the robot of FIG. 4;

FIG. 6 is a perspective view of another mobile robot stemming from therobot of FIG. 1 in accordance with certain embodiments of the invention,wherein the component units are joined while permitting the units to beadjusted in relation to each other;

FIG. 7 is a perspective view of a mobile robot stemming from the robotsof FIGS. 4 and 6 in accordance with certain embodiments of theinvention;

FIG. 8 is a perspective view of a magnet mount stemming from the mountof FIG. 5 in accordance with certain embodiments of the invention;

FIG. 9 is a perspective view of a magnet mount stemming from the mountsof FIGS. 5 and 8 in accordance with certain embodiments of theinvention;

FIG. 10 is a perspective view of a mobile robot stemming from the robotof FIG. 4 in accordance with certain embodiments of the invention, shownon an object with curved surface;

FIG. 11 is a perspective view of another mobile robot stemming from therobot of FIG. 4 in accordance with certain embodiments of the invention,showing an exemplary ganged arrangement on an object with curvedsurface;

FIG. 12 is a perspective view of an additional mobile robot stemmingfrom the robot of FIG. 1 in accordance with certain embodiments of theinvention, shown on an object with curved surface and wherein thecomponent units are joined while permitting the units to be adjusted inrelation to each other;

FIG. 12a is an enlarged perspective view of one joint area between thecomponent units of the robot of FIG. 12.

FIG. 13 is a perspective view of a mobile robot stemming from the robotsof FIGS. 6 and 12 in accordance with certain embodiments of theinvention, shown on an object with curved surface;

FIG. 14 is a perspective view of a mobile robot stemming from the robotof FIG. 13 in accordance with certain embodiments of the invention,shown on an object with curved surface;

FIG. 15 is an elevation view of an additional mobile robot stemming fromthe robot of FIG. 4 in accordance with certain embodiments of theinvention;

FIG. 16 is a master control diagram for the embodied mobile robots inaccordance with certain embodiments of the invention;

FIG. 17 is a control diagram for motor control system input for theembodied mobile robots in accordance with certain embodiments of theinvention; and

FIG. 18 is a perspective view of a mobile robot stemming from the robotof FIG. 6 in accordance with certain embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates one exemplary design of a mobile robot 1 inaccordance with certain embodiments of the invention. Mobile robots ofthe invention, such as the robot 1 of FIG. 1, have a framework, whereinthe framework includes one or more paired component units. For example,as shown, the mobile robot 1 includes a single pair of component units,unit 10 a and unit 10 b. The components units 10 a and 10 b are joinedtogether by component couplings 12. As illustrated, the couplings 12 caninvolve threaded members threaded through abutting faces of adjacentframes (or chasses) 11 for the two component units 10 a and 10 b so asto lock the units 10 a, 10 b together. However, as noted above, theinvention should not be limited to couplings for locking the componentunits together. For example, in alternate embodiments (as describedlater with reference to FIGS. 6, 7, and 12-14), the couplings can besubstituted with linkages. Such linkages allow for the joined componentunits to shift in relation to each other so that contact between theunits (e.g., wheels thereof) and the surfaces on which they traverse canbe maintained, regardless of the shape of, or irregularities present on,such surfaces.

In certain embodiments, as shown, each component unit 10 a and 10 b hasits own frame (or chassis) 11. However, if the component units 10 a, 10b are intended to be locked together via the component couplings 12,embodiments of the mobile robot could alternately employ a single framefor the units 10 a, 10 b. In certain embodiments, each component unit 10a and 10 b carries a pair of Mecanum wheels 20 a, 20 c and 20 b and 20d, respectively. However, as described above, Mechanum wheels representjust one of a variety of omni-directional wheels that can be used withmobile robots of the invention. In the case of the Mechanum wheels 20a-20 d, they can be rotatably mounted to the chassis 11 via wheel axles21 and can be independently driven. For example, in certain embodimentsas shown, each wheel is driven by its own drive motor 30 via a gearbox31. Further, each motor 30 can be independently controlled, such as by acontroller 32. This independent control, among other factors, enablesboth effective and efficient movement of the robot 1 on surfaces. Asshown, power packs (e.g., batteries) 40 of sufficient capacity can bemounted on one or more of the frames 11 to provide power to the motors30 and the motor controllers 32.

In certain embodiments, the mobile robot 1 includes magnets 50. However,it should be understood that magnets represent but one mechanism bywhich mobile robots of the invention can be held to surfaces (mostnotably, ferromagnetic surfaces) on which the robots are used,regardless of orientation of these surfaces to the ground or the floor.To that end, any mechanism acting to pull the robot toward, and hold therobot against, its working surface (so as to counteract gravitationalpull as applicable) would represent another of the mechanisms. Forexample, such mechanisms (used instead of or in combination withmagnetic force) would include vacuum force (as exemplified in FIG. 15)and clamping pressure (as exemplified in the embodiments described inU.S. Ser. No. 13/247,257, the disclosure of which is incorporated hereinby reference, in relevant part). Even further, another mechanism mayinvolve using differential force (e.g., via a pump, if the robot wereconfigured for underwater applications).

In using magnets to provide such holding force, the magnets 50 and anorientation control structure therefor are used. In certain embodiments,as shown, the magnets 50 are operably coupled to outer ends of the robot1. In some embodiments, the magnets 50 can be operably coupled to outerend surfaces of the robot 1; however, the invention should not belimited to such. Instead, one aim of embodiments of the invention is tohave the magnets 50 and their orientation control structure (as embodiedbelow) located external to the component units 10 a, 10 b. As shown, themagnets 50 and orientation control structure are provided adjacent to(or to the sides of) the units 10 a, 10 b. Such a configuration has manybenefits. For example, the magnets 50 and the orientation controlstructure can be incorporated with little to no modification beingnecessary for the design of the component units 10 a, 10 b. In addition,such configuration of the magnets 50 and orientation control structureenable one or more of the robot frame's clearance from the surfaces ittraverses, the robot's center of gravity, and the robot's overallprofile, to be kept at a minimum.

In certain embodiments, the magnets 50 are operably coupled to opposingends of the robot 1. In particular, as shown, each magnet 50 isoperatively coupled to the chassis 11 of its corresponding componentunit 10 a, 10 b. While FIG. 1 depicts a pair of the magnets 50 beingoperably coupled to each of the component units 10 a, 10 b, it should beunderstood that a single longitudinally-shaped magnet could instead beused with each unit 10 a, 10 b, or alternatively, magnet quantities oftwo of more could be used.

The embodied structure (the orientation control structure) by which themagnets 50 are operably coupled to mobile robots of the invention availselective adjustment of the magnets' positioning to the surfaces onwhich the robots are used. The orientation control structure involves aplurality of components. For example, as shown in FIG. 1, each magnet 50is operably coupled to the chassis 11 via a pivot member 52. In certainembodiments, each pivot member 52 can be pivotally mounted to a pivotaxle 53, which can be concentric with the wheel axle 21. Thus, in suchcases as shown, the magnets 50 can be externally offset from the wheels20 a-20 d of the robot 1. As shown for the robot 1 of FIG. 1, in certainembodiments, each pivot member 52 is generally shown as an L-shapedbracket, the leg of which is pivotally mounted on the pivot axle 53 andthe base of which is operatively coupled to the magnet 50 via fasteners.For instance, as shown in FIGS. 1 and 2, a threaded magnet adjustmentscrew 54 can be secured to each magnet 50, with the screw 54 beingcoupled to the base of the pivot member 52 using a magnet adjustment nut55. As shown, in certain embodiments, inward axial movement of the pivotmembers 52 (and consequently, the magnets 50) can be prevented via amagnet mounting bracket 51 which abuts a portion of the leg of the pivotmember 52. In such case, the bracket 51 can be either integrally formedto the chassis 11, or operably coupled to the chassis 11 as shown.

With continued reference to FIG. 2, in certain embodiments, the magnets50 are selectively adjustable in at least two dimensions in relation tothe surface 2 on which it traverses. For example, as shown, the magnets50 are selectively adjustable, both in orientation angle and clearancedistance in relation to the surface 2. Consequently, the magnets 50 canbe adapted to a variety of surfaces, from those with irregularitiesacross their extent to those that are non-planar, such as being curved.Regarding orientation angle, each magnet 50 is adjustable via pivotingof the pivot member 52 about the pivot axle 53. Regarding clearancedistance, the magnets 50 are adjustable (e.g., via the use of washersused with the adjustment screws 54) with regard to their position above(i.e., not contacting) the surface 2 on which the robot 1 is traversing.The clearance distance defines a gap 61 between the corresponding magnet50 and such surface 2. Such gap 61 (or clearance) between the magnets 50and the surface being traversed, prevents friction there between whilemaximizing the clinging power provided by the magnets. This ensures thatthe mobile robot 1 does not fall from the surface (and prevents slippagethereon), regardless of the surface's orientation. The magnets 50 can bepassive, such as neodymium, or active, such as electromagnets.Regardless of type, passive or active, the magnets 50 can be effectivelyused with the mobile robots of the invention, i.e., supported at adistance (greater than zero) from work surface to eliminate frictionbetween the magnets 50 and surface 2, yet provide sufficient force forholding the robots to the surface.

FIG. 3 shows the relationship of magnet force vs. distance for a genericneodymium magnet. The amount of magnetic force required for mobilerobots of the invention to operate on surfaces they traverse, regardlessof orientation, is defined by equation (1) below:

$\begin{matrix}{F_{Mreq} \geq \frac{M_{p}}{\mu_{mw}}} & (1)\end{matrix}$

-   -   Where:    -   F_(Mreq)=Magnetic Force Required for Adhesion to Ferrous Surface    -   M_(p)=Platform Mass    -   μ_(mw)=Mecanum Wheel Coefficient of Friction

The magnetic force is additive, meaning that each magnet 50 of themobile robot contributes to its overall lifting capacity. For example,looking to FIG. 3, if each magnet is held 0.2″ off the surface, thecorresponding magnetic force (F_(Mreq)) generated by each magnet isapproximately 90 lb (according to the FIG. 3 curve). With reference tothe mobile robot 1 of FIG. 1, this force would be multiplied by 4 inlight of the four magnets, totaling 360 lbs. Regarding this magneticforce, it should be appreciated how significant a role the gap 61 (orclearance) between the magnets 50 and the surfaces the robot 1 traversesplays in the intended functioning of the robot 1. To that end, theadjustability of the magnets 50 with regard to the traversed surfaces,made possible via the orientation control structure, enables such gap 61to be maintained.

Continuing use of equation (1) and the variables provided above, ifwheels, such as the Mecanum wheels 20 a-20 d, are used and havecoefficient of friction (μ_(mw)) of 0.35, the maximum lifting capacity(M_(p)) of the mobile robot 1 would be 126 lb. As a result, such robot 1can climb or descend surfaces, even when inverted (e.g., when traversingbottoms of elevated surfaces), without falling therefrom as long as thelifting conditions of equation (1) are met. As noted above, theadjustability of the magnets 50 enables their clearance (i.e., by thegap 61) with respect to the surface being traversed to be maintained,even on a cylindrical surface 2 as shown in FIG. 2. The same would holdtrue for movement over any other non-planar or uneven surfaces.

One purpose of mobile robots of the present invention is for them tocarry a payload (e.g., on exemplary payload brackets 13 as shown in FIG.7). Thus, in using equation (1), the payload capacity can beapproximated in using equation (2) shown below:M _(PL) =ΣF _(M)*μ_(mw) −M _(p)  (2)

-   -   Where:    -   ΣF_(M)=F_(M1)+F_(M2)+F_(Mx) . . . =Sum of Magnetic Force    -   M_(PL)=Payload Mass        Again using values from the example described above (ΣF_(Mr) is        360 lbs and μ_(mw) is 0.35), and defining the mass of the mobile        robot (M_(p)) to be 65 lb, the payload capacity (M_(PL)) would        be 61 lb.

With further reference to equation (1), there are various techniquesthat can be used to increase the lifting capacity (M_(p)) of theembodied magnetic mobile robots of the invention (such as robot 1 ofFIG. 1), several of which are noted below. However, what should beappreciated is that many of these techniques are made feasible due tothe magnets 50 and their orientation control structure being locatedexternal to the component units 10 a, 10 b of the robot 1. Sometechniques of increasing the lifting capacity (M_(p)) of the robot 1 caninvolve increasing the magnetic force (F_(Mreq)). One method of doing socan involve decreasing the distance of the magnets 50 to the worksurface to decrease the gap 61, thereby moving up the curve of FIG. 3and increasing the total magnetic force of the robot 1. Another methodcan involve increasing the number of magnets 50. An additional methodcan involve joining multiple robot segments together, each with acorresponding set of magnets 50 (such as depicted in FIG. 11, as laterdetailed). A further method can involve using more powerful or largermagnets 50.

Other techniques of increasing lifting capacity (M_(p)) can involveincreasing the coefficient of friction (μ_(mw)). For example, one methodof doing so can involve optimizing the material of the rollers 22 of theMecanum wheels 20 a-20 d to increase such coefficient of friction.Further techniques for increasing the lifting capacity (M_(p)) of therobot 1 can involve incorporating a lift or buoyancy generating deviceto the robot so as to effectively reduce the total mass lifted by therobot. As alluded to above, each of the techniques for enhancing therobot's lifting capacity involves adjustment of one of the threeparameters (F_(Mreq), M_(p), and μ_(mw)) of equation (1) above. However,it is to be understood that any combination of the above as well asother techniques can be used to increase the payload capacity, with thetechniques being simplified due to the positioning of the magnets 50 andtheir orientation control structure on robot 1.

Despite the above, one variable that can still affect payload capacityis material makeup of the surface that the mobile robots traverse. Aspreviously noted, while the magnets 50 function well in supporting themobile robots of the invention on ferromagnetic surfaces, alternativesupporting capability is necessary for traversing other surfacematerials. For example, in certain embodiments, a non-magneticallygenerated force can be added to the mobile robot to work alternately orin combination with the magnets 50, depending on the work surface. Asdescribed above, such non-magnetically generated forces can involvevacuum (e.g., under the chassis 11; see FIG. 15) and/or involve pressurefrom a multi-segmented device encircling the work surface 2 (e.g., seeembodiments described in U.S. Ser. No. 13/247,257).

As described above, mobile robots of the invention using Mecanum wheelsfor movement (such as the mobile robot 1 of FIG. 1) enable the robots tohave capacity for moving in any direction on a work surface. To thatend, Mechanum wheels represent one type of omni-directional wheels thatcan be used, so as to enable effective and efficient movement of therobots on a work surface. Such movement is made possible through thewheels being individually driven. For example, with regard to theMechanum wheels 20 a-20 d of the robot 1 of FIGS. 1 and 2, each containsa series of the rollers 22 attached to the wheel's circumference. Therollers 22 are generally configured to have an axis of rotation offsetby about 45° from a vertical plane of the wheel. As described above, incertain embodiments, each of the wheels 20 a-20 d can be configured withits own drive motor (or motion actuator) 30, and each of the drivemotors 30 can be connected to a controller 32. In such cases, eachcontroller 32 can communicate with a master controller 100 (with itsexemplary functioning being depicted in FIG. 16), such that the wheels20 a-20 d can be controlled to rotate in one of a variety of ways, suchas rotating (i) in the same direction at the same speed, (ii) in thesame direction differentially, (iii) in opposite directions at the samespeed, or (iv) in opposite directions differentially. Via suchcontrolled rotations, the mobile robots (and paired component unitsthereof) of the invention can be made to move in a variety ofdirections: sideways, diagonally, straight forward, or straightbackward, causing corresponding change of direction for the robot 1 tobe immediate and precise.

As shown in FIG. 1, wheels 20 a and 20 c are operably coupled tocomponent unit 10 a, and wheels 20 b and 20 d are operably coupled tocomponent unit 10 b. By rotating all wheels in the same direction at thesame speed, the robot 1 moves in that direction at the same speed.Alternately, by rotating wheels 20 c and 20 d to the aft (i.e., to therobot rear), and wheels 20 b and 20 a to the fore (i.e., to the robotfront), the robot 1 will shift laterally right edge of the paper asviewed in FIG. 1. Further, by reversing those directions, the robot 1will shift to the left edge of the paper as viewed in FIG. 1. Finally,by rotating wheels 20 b and 20 c to the aft, and wheels 20 a and 20 d tothe fore, the robot 1 will rotate in a clockwise direction. Reversingthose directions will cause the robot 1 to rotate in a counterclockwisedirection. Table 1 below summarizes the movement of the robot 1 withregard to such wheel actuations.

TABLE 1 Direction of Movement Mecanum Wheel Actuation Rearward (Aft) AllWheels Right Same Speed Forward All Wheels Left Same Speed Right Wheels20c, 20d rearward, 20a, 20b forward Left Wheels 20a, 20b rearward, 20c,20d forward CW Rotate Wheels 20c, 20b rearward, 20a, 20d forward CCWRotate Wheels 20a, 20d rearward, 20c, 20b forwardThus, by individually controlling the speed and direction of motors 30independently, the entire multi-unit robot device 1 can be made totraverse the work surface in any direction (forward, backward, laterallyleft, laterally right and any direction there between) in precise andimmediate manner. Clockwise and counterclockwise rotation would betypically used for small adjustments only in orienting the robot 1. Incertain embodiments, the total number of Mecanum wheels 20 used isdivisible by four, so as to enable unbiased motion.

It is to be appreciated that alternate magnet mount designs can be usedwithout departing from the spirit of the invention, as exemplified bymobile robot 1 a of FIG. 4. The magnets 50 of the robot 1 a (partiallyshown in FIG. 5) are used in a similar manner to those of the robot 1 ofFIG. 1. For example, like the magnets 50 for mobile robot 1 of FIG. 1,the magnets 50 are operably coupled to the robot 1 a so as to be heldabove, i.e., having no direct contact, with ferromagnetic surfaces ittraverses. Yet, the field strengths of the magnets 50 are sufficient(again using above-referenced equation (1) and equation (2) derivedtherefrom) to hold the robot 1 a and its payload against the surfaceswithout risk of falling therefrom.

Similar to the robot 1 of FIG. 1, in certain embodiments, the magnets 50are operably coupled to outer ends of the robot 1 a. Consequently, themagnets 50 and their orientation control structure (as embodied below)are located external to the component units 10 a, 10 b. As describedabove, this configuration has many benefits. For example, the magnets 50and the orientation control structure can be incorporated with little tono modification being made to the design of the component units 10 a, 10b. In addition, such incorporation of the magnets 50 and orientationcontrol structure enable one or more of the robot frame's clearance fromthe surfaces it traverses, the robot's center of gravity, and therobot's overall profile, to be kept at a minimum.

Similar to the robot 1 of FIG. 1, in certain embodiments, the magnets 50are operably coupled to opposing ends of the robot 1 a. In particular,as shown, each magnet 50 is operatively coupled to the chassis 11 of itscorresponding component unit 10 a, 10 b. While FIG. 5 depicts threemagnets 50 being operably coupled to each of the component units 10 a,10 b, it should be understood that one, two, or more than threemagnet(s) could instead be used with each unit 10 a, 10 b. In certainembodiments, as described below, the magnets 50 are exteriorly offsetfrom the wheels 20 a-20 d of the robot 1 a.

The embodied structure (the orientation control structure) by which themagnets 50 are operably coupled to the mobile robot 1 a is configuredfor working well with curved surfaces. To that end, the orientationcontrol structure avails selective adjustment of the magnets'positioning to the curve of such surfaces. Similar to the robot 1 ofFIG. 1, the orientation control structure of the robot 1 a of FIG. 4involves a plurality of components. For example, as shown in FIG. 4,each magnet 50 is operably coupled to the chassis 11 via a pivot member.To that end, the magnet pivot members 52 of robot 1 of FIG. 1 have beenreplaced by horizontally extending magnet pivot members 70 in robot 1 a.In certain embodiments, similar to the pivot members 52 of robot 1, eachpivot member 70 of robot 1 a can be pivotally mounted to a pivot axle53, which can be concentric with the axle 21 of the robot wheels andsupported by a mounting bracket 60. The bracket 60 can be eitherintegrally formed to the chassis 11, or operably coupled to the chassis11 as shown. While the mounting bracket 60 has a base member 61, similarto mounting bracket 51 of robot 1 of FIG. 1, the bracket 60 furtherincludes additional supporting structure. As shown, the bracket 60 caninclude a mounting flange 62 projecting away from base member 61 andchassis 11, terminating in a downwardly-turned flange 63. To that end,in certain embodiments, the pivot members 70 are pivotally mountedbetween the base member 61 and flange 63.

FIG. 5 shows an enlarged perspective view of one magnet pivot member 70of the robot 1 a of FIG. 4. As shown, each pivot member 70, generallyformed as a block 71, is made of non-ferrous material. In certainembodiments, the pivot member 70 has a pair of journals 72 projectingfrom opposing ends thereof. To that end, each journal 72 includes anopening 73 for receiving the pivot axle 53 generally extending frommounting bracket base member 61 to bracket flange 63.

It should be appreciated that the magnets 50 can be operably coupled tothe pivot member in a variety of manners. For example, with furtherreference to FIG. 5, the pivot member 70 can be equipped with a topplate 74, defining a plurality of openings 75, through which fastenersare passed for operably coupling same plurality of magnets 50 to themember 70. In certain embodiments, as shown, the fasteners used for eachmagnet 50 include an adjustment screw 54 and an adjustment nut 55, whichare mounted with respect to a top plate 74. In such case, each of theadjustment screws 54 is threaded at one end in one of the magnets 50 andat the other end through one of the adjustment nuts 55, which is shownas being mounted on a magnet suspension plate 76 further mounted to thetop plate 74 over one of the openings 75.

With continued reference to FIG. 5, in certain embodiments, the magnets50 are adjustable in at least two dimensions in relation to the surface2 on which it traverses. For example, as shown, the magnets 50 areadjustable, both in orientation angle and clearance distance in relationto the surface 2. Consequently, the magnets 50 can be adapted to avariety of surfaces, from those with irregularities across their extentto those that are non-planar, such as being curved. Regardingorientation angle, the magnets 50 of each pivot member 70 is adjustablevia pivoting of the member 70 about the pivot axle 53. Regardingclearance distance (similar to the gap 61 described above with referenceto robot 1 of FIG. 1), the magnets 50 are adjustable with regard totheir position above the surface 2 by rotating the adjustment screws 54in relation to the adjustment nuts 55. In certain embodiments, as shown,each pivot member 70 can include a pivot handle 77 secured to theoutside end journal 72, not only easing the manner to adjust the magnets50 in relation to the surface 2 but also easing the manner to move therobot 1 a in its entirety.

FIGS. 6 and 7 illustrate further alternative mobile robots 1 b and 1 c,respectively, in accordance with certain embodiments of the invention.The robots 1 b and 1 c respectively include component units 10 a and 10b and 10 a′ and 10 b′, yet the units are not locked with a couplingconnector (such as threaded couplings 12 of robot 1 of FIG. 1). Instead,the units 10 a, 10 b and 10 a′, 10 b′ are joined by one or more linkagesto permit shifting of the joined units in relation to each other. Incertain embodiments, as perhaps more clearly shown in FIG. 6, the one ormore linkages involve a single pivot or swivel joint coupling 12 a;however, the invention should not be limited to such as a wide varietyof other like-functioning linkages can just as well be used in thealternative.

However, in using the joint coupling 12 a as defining the one or morelinkages, at least some initial characteristics can be noted in its usewith the robots 1 b and 1 c. For example, in certain embodiments, theone or more linkages are located external to the component units (units10 a and 10 b of robot 1 b, and units 10 a′ and 10 b′ of robot 1 c).Additionally, in certain embodiments, the one or more linkages areoperably coupled to outer sides of two of the component units. Also, incertain embodiments, the one or more linkages are located along amidline of the robots 10 b and 10 c, but apart from wheel axles 21 ofthe robots.

In using the joint coupling 12 a as the one or more linkages, the joinedcomponent units (units 10 a and 10 b of robot 1 b, and units 10 a′ and10 b′ of robot 1 c) are configured for at least pivoting one of thecomponent units in relation to the other component unit. Thus, thejoined component units 10 a and 10 b, 10 a′ and 10 b′ are enabled toshift by a single degree of freedom. As previously described, using oneor more such linkages in joining the component units allows the units toshift (relative to each other) to better accommodate irregular surfacesover which mobile robots of the invention can be used. However, asalluded to above, other linkages could be used to enable more than onedegree of freedom being achieved for the units 10 a′, 10 b′. In certainembodiments, such linkage can also be also used with the Mecanum wheelsto maintain their contact with cylindrical surface 2 if there is any yawcomponent.

Continuing with reference to the robot 1 c of FIG. 7, several otherexemplary features are shown. For example, the frames (or chasses) 11for each of the units 10 a′ and 10 b′ can be covered to protect internalcomponents from an outdoor environment. Further, whether used separatelyor in combination, the units 10 a′ and 10 b′ can include generic payloadmounts 13 for carrying objects on the frames 11. In certain embodiments,additional Mecanum wheels 20 a′, 20 b′, 20 c′, and 20 d′ can be added tothe units for better distribution of the forces generated by the magnets50. Finally, in certain embodiments, robot 1 c also includes furtherwheels 14 and handles 15 attached to mounting flange 62′ to allow therobot 1 c to be transported like a hand cart. In such cases, the wheels14, as shown, can be mounted so as to not extend below the Mecanumwheels (toward the surface traversed by the robot 1 c). As such, thereis no interference or friction created by the wheels 14 contacting theworking surface when the robot 1 c is used. As further illustrated, themagnet brackets 62′ (e.g., locked to the units 10 a′, 10 b by removablepins 16) are configured to be removable from the robot 1 c. By removingthe pins 16, the brackets 62′ can be removed for robot 1 c storage andtransport.

FIG. 8 shows an additional alternative pivot member 70 a in accordancewith certain embodiments of the invention. Similar to the pivot member70 of FIGS. 4 and 5, the pivot member 70 a includes the same threadedadjustment screws 54; however, the screws 54 are secured to androtatably driven by adjustment motors 56. In certain embodiments, themotors 56 can be secured to a base member 77 of an inverted U-shapedstructure, with its legs 76 being secured to the top plate 74 of thepivot member 70 a. In such cases, the motors 56 can be adjustment screwmotors (as opposed to conventional stepper motors) to allow for precisecontrol of the heights of the magnets 50 above the surface traversed bythe corresponding mobile robot.

Similar to FIG. 8, FIG. 9 illustrates another alternative pivot member70 b in accordance with certain embodiments of the invention. As shown,distinct from the pivot member 70 a of FIG. 8, the legs 76 a of theU-shaped structure can be joined by cross members 77 a rather than a topplate 77. In addition, the adjustment rods 54 can be replaced bypneumatic or hydraulic cylinders 57 suspended between the cross members77 a (e.g., via suspension bolts 78 extending there between). In suchcase of using pneumatic or hydraulic cylinders 57, their piston rods 58are secured directly to the magnets 50. Consequently, the heights of themagnets 50 can be adjusted pneumatically or hydraulically. This can befound beneficial, particularly if the pistons 78 are spring biaseddownwardly. For example, in that event, if a control system (not shown)of the mobile robot detects that the robot is in danger of falling offof the ferromagnetic surface it is traversing, the control system cansend a signal to trigger cylinders 57 to extend cylinder rods 58downwardly as far as possible such that the magnets 50 directly engagethe ferromagnetic surface, thereby maximizing holding power.

FIGS. 10 and 11 show further alternative mobile robots 1 d and 1 e inaccordance with certain embodiments of the invention. Robot 1 d, whichis similar to mobile robot 1 a of FIG. 4, includes an additional pair ofmagnet pivot members 70 interposed between robot component units 10 aand 10 b. Such construction enables the magnet holding power afforded tomobile robot 1 d to be enhanced. It should be appreciated that this formof ganging technique could be further employed by continuing to add morealternating units 10 a and 10 b, separated from one another by pivotmounting members 70. Regarding ganging embodiments, FIG. 11 illustratesa configuration that closely resembles mobile robot 1 a of FIG. 4. Tothat end, FIG. 11 shows adjacent robots 1 a sharing the pivot members 70disposed between them. Ganging of robots is shown in only one axis, butganging can also be performed in a generally perpendicular axis alongthe surface 2, for example, by connecting the sides segments 10 a and 10b by a pivot or other joint coupling, such as later described and shownin FIG. 12.

Each mobile robot of embodiments of the present invention, or eachcomponent unit (units 10 a, 10 b of FIG. 1) thereof, can be utilized fora number of applications. For example, one exemplary set of applicationscan involve carrying a desired payload. The payload could be a spraypainting device, cleaning device, cutting device, welding device,inspection device, or other servicing device so that the mobile robotcan use such devices to clean, paint, inspect, or perform othermaintenance on a surface. When the robots are configured for traversingferromagnetic surfaces, objects having these types of surfaces couldinclude pipelines, towers, ship hulls, field erected tanks, beams, andother infrastructure. For tower applications, the payload could be acrane device which the robot would transport to the desired location ona tower, for use in raising, lowering and manipulating other equipment.In certain embodiments, more sophisticated payloads may require remotemanipulation of objects about the mobile robot 1. In such cases, therobots can be configured with one or more handling devices, such asrobotic arms, for carrying out such tasks.

FIG. 12 illustrates an additional alternative mobile robot 1 e inaccordance with certain embodiments of the invention. Similar to therobots 1 b of FIG. 6 and 1 c of FIG. 7, the robot 1 e of FIG. 12 has onedegree of freedom (e.g., pivoting) about joint coupling 12 b that allowsthe component units 10 a″ and 10 b″ to shift in relation to each other.However, by coupling the units 10 a″ and 10 b″ at two points (top andbottom corners of facing surfaces of the units), the joint coupling 12 bis even more effective in keeping the Mecanum wheels 20 perpendicular toand in flush contact with the surface 2. As a result, the robot 1 e canclimb a curved surface (such as surface 2) with all Mecanum wheelsturning in the same direction in smooth fashion. In certain embodiments,as perhaps most clearly shown in FIG. 12a , the joint coupling 12 b isheld by a pin 17 through angle set holes 18. Alternatively, for example,the pivot 12 b can be automatically adjusted with the addition of astepper motor and threaded rod arrangement similar to that shown in FIG.8, such that removal of pin 17 is precisely provided to control thepivot angle. As shown, the robot 1 e, in certain embodiments, includesmagnet holding brackets 71′. As shown, while these brackets 71′ areoperably coupled to ends of the robot 1 e, they allow for fixed magnetpositioning if adjustability of the magnets is not required. However, itshould be appreciated that pivot members (such as member 52 of robot 1of FIG. 1 or member 70 of FIG. 4) could be employed with robot 1 e.

As described above, in certain embodiments, mobile robots of theinvention use Mecanum wheels to achieve pure omnidirectional movement.However, other types of wheels or tracks can be alternately used as longas the requirements of equation (1) are met at the expense of pureomnidirectional movement. For example, such other types of wheels couldinclude conventional axis wheels 23 a-d (as exemplified in FIG. 13) orpivotable caster wheels to allow some degree of omnidirectionalmovement. On the other hand, if enhanced traction is dictated, theMecanum wheels 20 a-d or conventional axis wheels 23 a-d may be replacedwith tracks 24 a-d (as exemplified in FIG. 14).

With further reference to FIG. 13, it shows another alternative mobilerobot 1 f in accordance with certain embodiments of the invention. Tothis point, joint couplings used with the mobile robots have beendescribed as providing a single degree of freedom in shifting thecomponent units in relation to each other. However, with respect torobot 1 f, multiple linkages (e.g., joint couplings 12 a and 12 b) areexemplified, which via their combined use, enables dual degrees offreedom, each of which stem from facing sides 78 of the frames of thecomponent units 10 a″, 10 b″. One purpose in combining these jointcouplings is to provide robot 1 f with the degrees of freedom requiredto operate favorably on slight and severely irregular surfaces. As notedabove, the robot 1 f of FIG. 13 is exemplarily shown with conventionalaxis wheels 23 a-d in place of Mecanum wheels. However, some clockwiseand counterclockwise maneuverability is made possible for the robot 1 fgiven the dual degrees of freedom. For example, by rotating all wheelsin the same direction at the same speed, the robot units 10 a″, 10 b″move in that direction at the same speed. Additionally, by rotatingwheels 20 d and 20 b to the rear, and wheels 20 a and 20 c to the front,the units 10 a″, 10 b″ will rotate in a clockwise direction.Alternatively, reversing those directions will cause the units 10 a″, 10b″ to rotate in a counterclockwise direction. Table 2 below summarizesthe movement of the robot 1 f with regard to such wheel actuations.

TABLE 2 Direction of Movement Standard Wheel Actuation Rearward (Aft)All Wheels Rearward Same Speed Forward All Wheels Forward Same Speed CWRotate Wheels 20d, 20b Rearward, 20c, 20a Forward CCW Rotate Wheels 20a,20c Rearward, 20d, 20b Forward

FIG. 14 illustrates additional alternative mobile robot 1 g inaccordance with certain embodiments of the invention. Robot 1 g includesthe same configuration of the robot 1 f of FIG. 13; however, as notedabove, the robot 1 g is exemplarily shown with the conventional axiswheels 23 a-d (shown in robot 1 f of FIG. 13) having been replaced withtracks 24 a-d. Similar to the conventional wheels, limited clockwise andcounterclockwise maneuverability is possible given the dual pivotdegrees of freedom from the multiple linkages of the component units 10a″, 10 b″. By actuating all tracks in the same direction at the samespeed, the robot units 10 a″, 10 b″ move in that direction at the samespeed. By actuating tracks 24 d and 24 b to the rear, and tracks 24 aand 24 c to the front, the units 10 a″, 10 b″ will rotate in a clockwisedirection. Reversing those directions will cause the units 10 a″, 10 b″to rotate in a counterclockwise direction. Table 3 below summarizes themovement of the robot 1 g with regard to such wheel actuations.

TABLE 3 Direction of Movement Track Actuation Rearward (Aft) All TracksRearward Same Speed Forward All Tracks Forward Same Speed CW RotateTracks 20d, 20b Rearward, 20c, 20a Forward CCW Rotate Tracks 20a, 20cRearward, 20d, 20b Forward

FIG. 15 shows further alternative mobile robot 1 h in accordance withcertain embodiments of the invention. Robot 1 h includes the sameconfiguration of the robot 1 a of FIG. 4; however, the magnetic forcetherefrom is shown as being augmented by use of vacuum device 45. Asshown, in certain embodiments, the vacuum created from such device 45 ismaintained by a skirt 46 where the internal pressure is less thanexternal ambient pressure. Consequently, the vacuum provides a net force(that is movable across surface traversed by robot via action of thewheels, e.g., Mecanum wheels 20 a-) similar to that generated by magnets50. It should be understood that while a vacuum may be part of theoverall payload where it is required to remove debris, such as a sandblasting application, as the vacuum can serves to augment the holdingforce applied to the robot wheels in addition to the primary role ofremoving debris. If vacuum 45 is sufficiently strong enough to ensurethe requirements of equation (1) are met, the magnets 50 are notrequired for mobile robots of the invention. It is to be appreciatedthat in such scenarios, the work surface needs not be ferrous, butinstead only sufficiently smooth to allow the skirt 46 to maintainsufficient vacuum.

In certain embodiments, each mobile robot 1-1 h embodied herein, or eachcomponent unit thereof, may include quick connect/disconnect interfaces,e.g., for electrical power, control communications, pneumatic/hydrauliclines for use by payload and robot, if required, and application liquidlines for use by payload, if required. Additionally, in certainembodiments, each component unit of the embodied robots can be made to asize which provides room to install all equipment necessary to make itand the payload self-contained (e.g. batteries, tanks, wirelesscommunication, etc.). This would be desirable if the robot needs tonavigate around supporting structure or large obstacles that makepower/control lines impractical (e.g. pipeline supports).

The mobile robots of the invention, in any of their various embodiments,can be controlled through a “master controller” computer 100, anexemplary master control diagram for which is provided in FIG. 16 inaccordance with certain embodiments of the invention. Whether usingMecanum wheels 20 a-20 d, conventional axis wheels 23 a-23 d, or tracks24 a-24 d, such are independently controlled to achieve the desiredmovement on the object that the robot is traversing. In certainembodiments, such control can also be provided for operable payloaddevices carried by the robot. Thus, the master controller computer 100can be configured to independently direct a plurality of individualactuator controls A1, A2, A3, . . . , AN (e.g. motor controller 32),depending on the quantity needed to control all of the wheels (or tracksand operable payload members) mounted on the robot, or robots if theyare ganged together (such as exemplified in FIG. 11). The controllercomputer 100, in certain embodiments, is independently wired to each ofthe actuator controls in each of the robots; however, the inventionshould not be limited to such, as the controller computer 100 couldalternately control each actuator control through wirelesscommunications.

FIG. 17 is a control diagram for motor control system input for theembodied mobile robots in accordance with certain embodiments of theinvention. To begin, actuator input from the master controller computer100 is individually directed as indicated by control lines 101 to eachactuator control A1, A2, A3, . . . , AN, such as motor controller 32,located on the robot or robots. The actuator control, as shown,processes the information and directs an actuator, e.g. a motor 30, toperform a desired function. The so-directed actuator then providesfeedback information to the actuator control, which in turn feeds itback to the master controller computer 100, as indicated by one or morefeedback lines 102. It should be appreciated that lines 101 and 102 caninvolve wireless lines of communication as well as wired lines.

FIG. 17, in particular, is an exemplary schematic of actuator controlsystem A1, which controls a wheel or track drive motor 30. As shown, themaster controller 100 sends angular rate instructions to a motorcontroller 32, as indicated by line 101. This signal passes through asumming point 121 and on to the motor controller 32, which in turnpasses these instructions on to motor 30 via line 104. The motor 30provides an output signal which is fed back to the master controller100, and can be fed to a potentiometer/encoder 123 via communicationline 105. In such case, the potentiometer/encoder 123 measures the rateof rotation of motor 30, and sends the resulting signal to the summingpoint 121 via communication line 107. The resultant feedback signal iscommunicated to the motor controller 32 via communication line 108. Themotor controller 32, in turn, compares the two inputs and can send ablended resultant signal via line 104 to wheel or track drive motor 30.

With reference, for example, to a process involving instructions for asurface to be cleaned, painted or otherwise treated, instructions can beloaded into the computer/controller 100 in a program similar to a CNCmachining program. The controller 100 then instructs the mobile robot,through various actuator control systems A1-AN, on how to move to aspecific location or cover the surface completely. The computer candetermine the starting point of robot by the configuration of the robotat whatever point from which it starts on the work surface. Alternately,if automated control is not required, the mobile robot can be manuallycontrolled by an operator.

Alternatively or in combination, location control can be based on anexternal reference source. For example, the reference source could relayglobal position of specific point(s) of reference on the robot or gangedrobots, to the master controller 100. By comparing the external positionreferences to the robot position(s), the controller 100 would be able toprocess an accurate position reference for the robot or each gangedrobot, or robot unit components. There are several methods of externalcontrol possible, with one common method involving GPS or a groundtransmitter being located in a known position.

In certain embodiments, position and/or orientation of the robot can bedetermined by feedback from a wide array of sources (e.g. pitch and yawangle sensors, GPS, accelerometers, coasting encoder wheels, knownposition transmitter, drive motor rates, inertial guidance control,etc.). As should be appreciated, precise position and orientationcontrol allows for minimal user input, and thus facilitates automationof a particular task. The robot will relay relevant position data to thepayload as required. FIG. 18 illustrates an exemplary mobile robot 1 ihaving features for enabling certain of these functions in accordancewith certain embodiments of the invention. Similar in many respects tothe robot 1 b of FIG. 4, the robot 1 i has further features includingomni wheel 25, omni-wheel encoder 123 a, and joint coupling encoder 123b. In certain embodiments, as shown, the omni wheel 25 is pivotallycoupled to the magnet mounting bracket 51 so as to freely contact androtate on the work surface that the robot 1 i traverses. As furthershown, in certain embodiments, the wheel encoder 123 a is coupled to theaxle of the wheel 25, while the joint coupling encoder 123 b is coupledto one end of the joint coupling 12 a between the component units 10 a,10 b.

With continued reference to FIG. 18, via monitoring of the velocity andposition of the wheel 25, the wheel encoder 123 a transmits suchinformation to the master controller 100 (not visibly shown but locatedon one of the component units 10 a, 10 b). With this information, thecontroller 100, among other things, is able to track true position ofthe robot 1 i on the work surface. Similarly, the joint coupling encoder123 b can monitor angle difference between the component units 10 a, 10b and transmit such information to the master controller 100. It shouldbe appreciated that the greater the angle difference, the more off axisthe robot 1 i is in relation to the working surface. This isparticularly relevant with curved working surfaces. As some amount ofwheel slip is inherent in Mecanum drive systems, in certain embodiments,feedback in addition to Mecanum wheel rates as supplied to the mastercontroller 100 can allow for precise control of robot 1 i orientationand accurate navigation. To that end, the controller 100 can correct forany slipping as the robot 1 i moves along the surface via control of thevarious actuator control systems A1-AN. Slip is less of an issue forconventional axis wheel or track drive systems, but for precise control,master controller 100 would still require feedback.

The robots of the preferred embodiments have many uses, one of which isservicing cylindrical towers, such as wind turbine towers or verticalpipe. The configuration of the tower, such as location of protrudingobstacles and other general “keep-out” zones, can be loaded into thecomputer/controller 100 in a program similar to a CNC machining program.In turn, computer/controller 100 can compare the configuration of mobilerobot to the configuration of the tower to determine the startingposition of robot. In use, the mobile robot may be placed on any ferroussurface and surface geometry provided to the controller 100. In certainembodiments, as alluded to above, an onboard GPS or other navigationdevice can be used to communicate position and orientation informationto the computer/controller 100. The computer/controller 100 theninstructs the mobile robot, through various actuator control systemsA1-AN, on how to move in order to proceed to and on the surface, so asto cover the surface completely or move directly to a particularlocation thereon. As described above, the mobile robot can carrycleaning, painting, cutting, welding, and/or other servicing equipment,which the computer/controller 100 can instruct the robot to both prepareand then service the work surface.

It should be understood that the foregoing is a description of preferredembodiments of the invention, and various changes and alterations can bemade without departing from the spirit of the invention.

What is claimed is:
 1. A mobile robot configured to be used on aferromagnetic surface, regardless of orientation of the surface toground or floor, the mobile robot comprising: a framework; and aplurality of magnets, the magnets being operably coupled to theframework and maintained at a set height relative to the framework and acorresponding distance above the ferromagnetic surface during movementof the mobile robot and at which field strengths of the magnets aresufficient to hold the robot and payload thereof against the surface,the plurality of magnets including at least a first set of magnetsoperably coupled to outer ends of the framework.
 2. The mobile robot ofclaim 1 wherein the ferromagnetic surface is of an object having one ormore portions angled from the ground or floor.
 3. The mobile robot ofclaim 2 wherein the object is a wind turbine tower.
 4. The mobile robotof claim 1 wherein the magnets are selectively adjustable in two or moredimensions in relation to the ferromagnetic surface.
 5. The mobile robotof claim 4 wherein the magnets are selectively adjustable with regard toangle and clearance in relation to the ferromagnetic surface.
 6. Themobile robot of claim 1 wherein certain of the first set of magnets areoperably coupled to one end of the framework, and remainder of the firstset of magnets are operably coupled to an opposing end of the framework.7. The mobile robot of claim 6 wherein the magnets are operably coupledto the framework via orientation control structure, the orientationcontrol structure comprising a plurality of pivot members.
 8. The mobilerobot of claim 7, wherein each pivot member is formed as an “L” bracket,wherein each “L” bracket has a leg segment that is pivotally adjustableto the ferromagnetic surface, and each “L” bracket has a base memberthat operably supports one of the magnets while permitting verticaladjustment of the one magnet to the ferromagnetic surface.
 9. The mobilerobot of claim 7, wherein each pivot member is formed as a block that ispivotally adjustable to the ferromagnetic surface, and defined with oneor more vertical openings there through and plates thereon for operablysupporting a same one or more of the magnets while permitting verticaladjustment of the magnets to the ferromagnetic surface.
 10. The mobilerobot of claim 1 wherein the framework comprises one or more pairs ofcomponent units, wherein each of the component units is an integralassembly and has a frame surrounding the assembly, and wherein thecomponent units of each pair are operably joined in a side-by-sidemanner.
 11. The mobile robot of claim 10 wherein the plurality ofmagnets includes a second set of magnets, wherein the second set ofmagnets is operably coupled between at least one of the component unitpairs.
 12. The mobile robot of claim 10 wherein the framework comprisesone pair of component units.
 13. The mobile robot of claim 12 whereincertain of the magnets are operably coupled to a first component unit ofthe one pair and remainder of the magnets are operably coupled to asecond component unit of the one pair, the magnets being on opposingsides of the first and second component units.
 14. The mobile robot ofclaim 10 wherein the frames of the component units of the one pair areoperably joined via one or more component couplings.
 15. The mobilerobot of claim 14 wherein the joined component units are locked inrelation to each other via the component couplings.
 16. The mobile robotof claim 14 wherein one or more of the component couplings compriselinkages, wherein the linkages are configured to permit the joinedcomponent units to shift in relation to each other so that contactbetween the robot and the ferromagnetic surface is maintained.
 17. Themobile robot of claim 16 wherein the joined component units are enabledto shift in relation to each other in more than one degree of freedom.18. The mobile robot of claim 17 wherein one of the degrees of freedominvolves the joined component units being able to pivot in relation toeach other.
 19. The mobile robot of claim 1 wherein orientation of theplurality of magnets relative to the ferromagnetic surface isself-regulated by the magnets during movement of the robot.
 20. Themobile robot of claim 1 whereby the height and corresponding distance ofthe plurality of magnets result in keeping to a minimum one or more of(i) clearance of the framework from the ferromagnetic surface, (ii)center of gravity of the robot, and (iii) overall profile of the robot.